Tankless Water Heater Size Calculator

Tankless Heater Sizing Formula:

\[ \text{Total GPM} = \sum (\text{Fixture GPM}) \]

Total GPM Required:

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1. What is Tankless Water Heater Sizing?

Tankless water heater sizing involves calculating the total flow rate (GPM - gallons per minute) required to meet your household's hot water demands. Proper sizing ensures you have adequate hot water supply without oversizing the unit.

2. How Does the Calculator Work?

The calculator uses the simple formula:

\[ \text{Total GPM} = \sum (\text{Fixture GPM}) \]

Where:

Fixture GPM — Flow rate of individual fixtures (showers, faucets, etc.)
Total GPM — Sum of all fixture flow rates that might run simultaneously

Explanation: The calculation sums up the flow rates of all fixtures that may be used at the same time to determine the required tankless heater capacity.

3. Importance of Proper Sizing

Details: Correct tankless water heater sizing is crucial for energy efficiency, consistent hot water supply, and avoiding unnecessary costs from oversized units. Undersized units may not meet demand during peak usage.

4. Using the Calculator

Tips: Enter the total flow rate of fixtures that may run simultaneously in gallons per minute (GPM). Consider typical usage patterns in your household for accurate sizing.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical GPM requirement for a household?
A: Most households require 5-7 GPM, but this varies based on the number of bathrooms and fixtures.

Q2: How do I calculate fixture GPM?
A: Check manufacturer specifications for each fixture or use standard values: shower (2.5 GPM), faucet (1.5 GPM), dishwasher (1.5 GPM), washing machine (2.0 GPM).

Q3: Should I consider temperature rise in sizing?
A: Yes, temperature rise (difference between incoming and desired water temperature) affects sizing. Colder climates may require higher capacity units.

Q4: Can I run multiple fixtures simultaneously?
A: The calculator helps determine if your tankless heater can handle multiple fixtures running at the same time based on total GPM requirement.

Q5: What about gas vs electric tankless heaters?
A: Gas units typically have higher flow rates than electric models. Consider energy source availability and installation requirements.